DESCRIPTION The project will study the feeding arousal state in a mollusc model available in Russia, using a 120-channel optical recording set-up used by the Russian investigators. The optical recording technique, combined with intracellular stimulation of identified cells, will allow simultaneous monitoring of a number of neurons in the relevant network. This will provide information about the spread of activity in the network during afterdischarges and will reveal modifications occurring in the network during the feeding arousal state that dramatically increase the responsiveness of the system. The simplicity of the preparation, including its behavior and underlying neural circuit, makes it possible to draw direct connections between the changes in the activities and connections of individual neurons in the underlying neural network and its behavioral outputs. This task is much more difficult, if at all possible, in complex organisms such as vertebrates.